How do you solve the equation $x^{2} + 1.4 x = 1.2$ $x^2+1.4x=1.2$ by completing the square?

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Answer 1 · 2017-05-19T14:30:37

$x = 0.6$ $x=0.6$ or $x = - 2$ $x=-2$

Divide the coefficient of the $x$ $x$ term by $2$ $2$ and square it.

$\frac{1.4}{2} = 0.7$ $1.4/2=0.7$

${(0.7)}^{2} = 0.49$ $(0.7)^2=0.49$

Now add it to both sides of the equation

$x^{2} + 1.4 x + 0.49 = 1.2 + 0.49$ $x^2+1.4x+0.49=1.2+0.49$

This becomes

${(x^{2} + 0.7)}^{2} = 1.69$ $(x^2+0.7)^2=1.69$

Take the square root of both sides

$\sqrt{{(x + 0.7)}^{2}} = \pm \sqrt{1.69}$ $sqrt((x+0.7)^2)=+-sqrt(1.69)$

$x + 0.7 = \pm 1.3$ $x+0.7=+-1.3$

$x = \pm 1.3 - 0.7$ $x=+-1.3-0.7$

$x = 1.3 - 0.7 = 0.6$ $x=1.3-0.7=0.6$

$x = - 1.3 - 0.7 = - 2$ $x=-1.3-0.7=-2$

How do you solve the equation x^2+1.4x=1.2x2+1.4x=1.2x^2+1.4x=1.2 by completing the square?